Polimorfismo como estratégia de proteção contra predação por aves: estudo experimental com lagartas artificiais

Abstract

Predation can be considered one of the strongest interactions between individuals in ecological communities, as the predator increases its fitness and controls the population of its prey. Many species spend part of their lives avoiding predators and a good way to avoid them is through phenotypic variations. Polymorphism is known as a protection strategy against predation, resulting in an increase in the individual survival rate in polymorphic populations, by hindering the formation of the search image by the predator. The aim of this study was to test the protective effect of polymorphism in artificial caterpillars against predation by birds. Our hypothesis was that polymorphism influences the predation rate of artificial caterpillars by birds, and our prediction was that polymorphic populations would be less predated when compared to monomorphic populations. 1280 artificial caterpillars were made, mimicking lepidopteran larvae, in four different color patterns: green, black, red and orange. These caterpillars were grouped into 32 monomorphic and 32 tetramorphic populations, each population containing 20 individuals arranged in leaf substrate at eight different points in forest fragments in the municipality of Analândia/SP. Complementarily, a qualitative survey of bird species that occur in the study area was carried out to verify possible predators of artificial caterpillars. Contrary to prediction, polymorphic populations suffered more predation when compared to monomorphic populations. Other than that, green monomorphic populations were not predated. It is believed that the general low rate of predation of caterpillars by birds due to the low species richness of insectivorous birds, the lack of behavioral responses by artificial prey and the success of the camouflage strategy by green individuals have contributed to this result. .